Interesting bit: The Battle of Barnet had one of the most tragic outcomes of any of the battles during the Wars of the Roses. Human error can often have a
devastating effect, and this was no exception.

On the night of 13th April, King Edward IV ordered his army through Barnet
to the northern side of the town and set up camp there. Richard Neville, the
Earl of Warwick's army was assembled on a ridge, also to the north of
Barnet. Edward's unorthodox manoevre had far reaching consequences, as in
the darkness, the two armies took up positions much closer together than
either commander realised. Also, instead of lining up directly opposite each
other (as was standard procedure for the time), each right flank extended
past the opposite left flank.
Warwick's scouts had informed him that the enemy were ahead of him in the
darkness somewhere, so he ordered several shots of artillery in their
direction. The cannon fire overshot it's mark due to the short distance
between the armies and as a result, Warwick's position was now known to
Edward, while Warwick remained unaware of the Yorkist's location.

Sometime between 3:00am and 4:00am, both armies prepared for battle,
shrouded by heavy fog. For the rebels, the Earl of Oxford commanded the
right flank (vanguard), Sir John Neville, Lord Montagu (Warwick's brother)
commanded the centre, and the Duke of Exeter commanded the left flank
(rearguard). Warwick himself commanded a reserve of men, slightly uphill and
behind the main force. For Richard Neville, it was a bitter moment. This was
his last chance to overthrow the King of England, his cousin. With him was
his younger brother John, whom he trusted, but who had been all but forced
into his opposition of his beloved King who he had served for so long. Most
of Warwick's other leaders were his old Lancastrian enemies, and on top of
all this, he had been deserted by his own son-in-law. For the Yorkist side,
the commanders were Lord William Hastings on the rearguard; Edward's brother
Richard, the 18 year old Duke of Gloucester led the vanguard; and Edward
himself in the centre.

When the battle actually began at 4:00am, the field was still covered in
very dense fog. Therefore it was not until the two armies clashed,that they
realised they overlapped each other's left flanks. With both rearguards
giving way, the entire front turned almost 90 degrees. While Gloucester's
force fought fiercely with the left flank under Exeter's command, the
Yorkist left flank broke and fled towards Barnet. Oxford's men pursued them,
and began plundering the town.

Because of the fog, Edward's centre was unaware of the fate of Hastings'
men, and the fighting continued between the remaining armies. Reserves were
brought up on both sides, but the Yorkists were slowly being pushed back. It
seemed to Warwick that he would be victorious, particularly when he had word
from Oxford that he had rallied his men and would return to the field.

This was where things really started to go awry.

The Earl of Oxford, with around 500 mounted men-at-arms returned to the
battle. Due to the fog, they were not aware that the front line had changed
direction, and charged into what they believed to be the rear of Edward's
army. In reality, they clashed with the men under Montagu's command - the
centre of Warwick's force. Montagu became aware that he was under attack,
and mistook Oxford's banner of a star and streams for Edward's banner of a
sun and streams. In what must have been a heart-breaking decision, he
ordered his archers to open fire on men he believed to be his cousin's.
Oxford's men, now mistakenly believing that Montagu had turned traitor to
Warwick, began crying "treason". Although King Edward had no idea that the
Lancastrian vanguard and centre were now fighting each other, he sensed
trouble and spurred his men forward into the enemy line in a flurry of
attack.

As Warwick's men realised they were defeated and fled the field, the
Yorkists pursued them in all directions. Warwick himself was killed during
the rout by Yorkist men-at-arms. His brother John, Lord Montagu (also
killed) is said to have been wearing the King's colours under his armour, an
indication that underneath his sense of duty to his brother, lay even deeper
loyalty to his cousin, King Edward IV.